1. Field of the Invention
The invention relates to a particular wall configuration for an inlet air passage for introducing air into an internal combustion engine, primarily of the direct injection diesel type. The particular wall configuration forming the passage of the present invention provides a large amount of swirl, excellent flow coefficient and, in some instances, means for controlling the amount of swirl to optimize engine performance under various operating conditions.
2. Prior Art
It is known to provide vanes or swirlers within the inlet air passage of internal combustion engines to create swirl in the air which passes through the valves of such engines. In one such prior art inlet air system the passage walls create the major swirl while a vane serves to oppose the swirl and introduces a portion of the air passing through the valve pack into the cylinder bore in an opposite direction to the majority of the air passing through the valve into the cylinder bore. This creates turbulence but is, of course, wasteful of energy since air must first be introduced in one direction and then a portion of it must be stopped and redirected in the opposite direction. It is inevitable that a certain amount of reduction in the flow coefficient of such an air system results. Inlet passages have been designed of this nature which utilize both stationary and adjustable vanes or spoilers.
Another prior art design utilizes a rotatable vane which nests against the upper wall of the inlet passage when the engine is running at normal speed and thus does not contribute to swirl of the air in that condition. When the engine is started up and when a cold engine is idled the vane is rotated down from the upper wall of the passage and used to reduce or eliminate swirl whereby the vane in this design also acts as a spoiler as far as air flow is concerned.
Adjustment of flow without reduction thereof or increases in fuel consumption would be very desirable. Yet, the prior art has provided neither of these results.